Cross-test HD key derivation between Ledger device, Namada extension, and SDK implementation

[cwgoes]

We should be able to:

• export a mnemonic from the SDK, import it into the Ledger device, and derive the same keys (as the SDK)
• export a mnemonic from the Ledger device, import it into the SDK, and derive the same keys (as the Ledger device)

[cwgoes]

Note: If we import the SDK into the extension instead of using native HD code, we should test against an external HD library, e.g. this one, and make sure the outputs match.

[adrianbrink]

@sug0 @murisi did one of you complete this?

[sug0]

I only tested an independent implementation (https://github.com/heliaxdev/namada-wallet-go) against namadaw.